This invention relates to a setup of instrumental indication display on an instrument board in an automobile, utilizing a panel type indicator such as a liquid crystal panel or an electroluminescence panel.
Recently, panel type indicator units for the display of the indications of automotive meters are under development by utilizing panel type electronic display means such as liquid crystal (LC) panels, electroluminescence (EL) panels, electrochromic (EC) panels and plasma panels since this type of indication display units can be made very small in size, light in weight and simple in construction and accordingly are quite advantageous to automotive meters.
Common to these panel type indication display units, it is necessary to employ a sandwich structure comprising a planer display element (for example, a liquid crystal layer or an electroluminescence layer) sandwiched between two transparent layers such as glass plates or synthetic resin plates. Unlike glass plates for conventional automotive instruments, panel type indication display units of such a sandwich structure can hardly be produced as convex panels or concave panels on an industrial scale since the distance between the two transparent plates must be uniform over the entire area with extremely high precision, i.e. with tolerance only in the order of micron. In other words, panel type indication display units for automotive meters can be available only in the form of entirely and completely flat panel. When such a flat display unit is mounted on an instrument board in the same manner as the mounting of conventional meter indicators, there arises a problem that the reflection of light rays incident on the display face of the display unit through windows of the car is likely to interfere with the driver's recognition of the displayed indications. To avoid the interference by the reflected light thereby to confirm the displayed indications, the driver will be obliged to move his head so as to shift the positions of his eyes. This will present a serious inconvenience to the driver and will irritate him.